Honda Civic. Manual — part 778

Fig. 121: Inserting Thermometer In Center Vent

5. Place a thermometer (B) near the blower unit's recirculation inlet duct.
6. Test conditions:

Avoid direct sunlight.

Open hood.

Open front doors.

Set the temperature control dial to Max Cool, the mode control switch to
Vent, and the recirculation control switch to Recirculate.

Turn the A/C switch ON and the fan switch to Max.

Hold the engine speed at 1,500 rpm.

No driver or passengers in vehicle.

7. After running the air conditioning for 10 minutes under the above test

conditions, read the delivery temperature from the thermometer in the center
vent, the intake temperature near the blower unit, and the discharge (high) and
suction (low) pressures on the A/C gauges.

8. To complete the charts:

Mark the delivery temperature along the vertical line.

Mark the intake temperature (ambient air temperature) along the bottom
line.

Draw a line straight up from the air temperature to the humidity.

2008 Honda Civic EX

2006-08 HVAC Heating/Air Conditioning - Civic (All Except Hybrid)

From each point, draw a horizontal line across the delivery temperature.

The delivery temperature should fall between the two lines.

Complete the low-side pressure test and high-side pressure test in the same
way.

Any measurements outside the line may indicate the need for further
inspection.

Example

Intake temperature (dry): 86°F (30°C) Humidity level 70%
Intake temperature (wet): 77.9°F (25.5°C)
Delivery temperature: 61°F (15.9°C)

Intake pressure: 261 kPa (2.7 kgf/cm

2

(38psi)

Delivery pressure: 1,780 kPa (18.2 kgf/cm

2

(258 psi)

Results: Within normal range

2008 Honda Civic EX

2006-08 HVAC Heating/Air Conditioning - Civic (All Except Hybrid)

Fig. 122: A/C System Test Graph

PRESSURE TEST

PRESSURE TEST DESCRIPTION

Test results Related symptoms

Probable cause

Remedy

Discharge
(high)
pressure

After stopping A/C
compressor,
pressure drops about
196 kPa (2.0

kgf/cm

2

,28 psi)

quickly, and then
falls gradually.

Air in system

Recover, evacuate (see
REFRIGERANT
RECOVERY ), and
recharge with specified
amount (see SYSTEM
CHARGING ).

Clogged
condenser or
radiator fins

Clean

2008 Honda Civic EX

2006-08 HVAC Heating/Air Conditioning - Civic (All Except Hybrid)

abnormally
high

Reduced or no
airflow through A/C
condenser.

A/C
condenser or
radiator fan
not working
properly

Check voltage and
fan rpm.

Check fan direction.

Line to A/C
condenser is
excessively hot.

Restricted flow of
refrigerant in
system

Restricted lines.

Discharge
pressure
abnormally
low

High and low-
pressures are
balanced soon after
stopping A/C
compressor. Low
side is higher than
normal.

Faulty A/C
compressor
discharge
valve

Faulty A/C
compressor
seal

Replace the A/C
compressor.

Outlet of expansion
valve is not frosted,
low-pressure gauge
indicates vacuum.

Faulty
expansion
valve

Moisture in
system

Replace.

Recover, evacuate,
and recharge with
specified amount.

Suction
(low)
pressure
abnormally
low

Expansion valve is
not frosted, and low-
pressure line is not
cold. Low-pressure
gauge indicates
vacuum.

Frozen
expansion
valve
(Moisture in
system)

Faulty
expansion
valve

Recover, evacuate,
and recharge with
specified amount.

Replace the
expansion valve.

Discharge
temperature is low,
and the airflow from
vents is restricted.

Frozen evaporator

Run the fan with A/C
compressor off, then
check evaporator
temperature sensor.

Expansion valve is Clogged

Clean or replace.

2008 Honda Civic EX

2006-08 HVAC Heating/Air Conditioning - Civic (All Except Hybrid)